Not applicable
This invention relates to vacuum collectors, specifically to cyclonic vacuum collectors employing HEPA (High Efficiency Particulate Air) filters to achieve large-scale environmental remediation.
3.1. Environmental Remediation: A Critical Problem Accompanying Sandblasting
Sandblasting is an important preliminary to the painting of large metallic structures, e.g., bridges. Sandblasting removes old paint and cleans the bridge to be painted. Sandblasting produces large quantities of reactive, toxic dust. Significant amounts of neurotoxic lead, carcinogenic chromium, and other highly toxic materials make this dust very dangerous. Collecting paint dust from sandblasted bridges in a safe manner is necessary and presently extremely difficult. Federal regulations require that vacuum collectors picking up paint dust have HEPA filters to ensure their exhaust is better than 99.97% free of dust particles greater than 0.3 micron in diameter. At present, there are no small portable vacuum collectors that can pick up large amounts of sandblasted materials according to these federal regulations. Therefore, there is a great need for a portable vacuum collector, which protects the sandblaster and enables environmental remediation in accordance with the law.
3.2. Environmental Remediation: A Critical Global Problem
Bridge-sandblasting does not alone pollute the environment. Many economic activities, such as manufacturing, building, infrastructure maintenance, etc., create toxic byproducts which are dispersed in the land, sea, and air. These toxic byproducts harm or destroy life and, with economic activities across the globe at historical maxima, the remediation, i.e., the cleaning and restoration, of the harmed environment is now a critical planetary need.
Solids, such as heavy metals (e.g., lead, mercury, chromium, zinc, etc.), chemical compounds of heavy metals, asbestos, other toxic substances, etc., occasionally mixed with liquids, are a major part of environmental pollution. The best way to deal with such materials is to pick them up using the precise action of a vacuum collector or cleaner, transfer them to a container, and seal and bury this container, in a suitable place.
The vacuum collector this cleaning operation requires is small but powerful, armed with a HEPA filter, which insures exhaust air of high purity, and able to handle large-scale cleaning, including dust removal, nonstop. The desired vacuum collector is also simple as well as inexpensive, to buy and operate, since a significant amount of solid pollutants is created by small contractors, manufacturers, builders, and others, who lack the resources to conduct complicated, costly remediations. As the following discussion of the prior art shows, this vacuum collector is presently unavailable, and this lack both prevents enforcement of federal environmental standards and destroys the environment.
3.3. Prior Art
(a) U.S. Pat. No. 4,753,639 to Johnstone describes a vacuum loader employing an air blower, a filtering module, and a debris collector. The blower sucks debris-laden air into the debris collector, some of the debris is gravitationally deposited in the collector, the partially cleaned air then goes through the filters and ultimately into the atmosphere. Lack of powerful cyclonic cleaning, among other things, makes this vacuum loader unsuitable for challenging operations.
(b) U.S. Pat. No. 4,133,658 to Callewyn describes a dust collector employing a single cyclone-producing module, which is mounted on a dust collector, and a blower. The blower sucks dust-laden air into the cyclone module, the air spins depositing dust into the dust collector below, and then goes through a vortex device inside the cyclone chamber, out of the cyclone chamber, into an external filter bag, and finally into the atmosphere. Although more potent than analogous non-cyclonic appliances, this appliance cannot efficiently clean heavily contaminated areas, because, among other deficiencies, it has only one cyclone.
(c) U.S. Pat. No. 5,080,697 to Finke describes a pull-down vacuum cleaner of one module containing a conical cyclone generator as well as primary and secondary filters, with the primary filter covering the bottom of the module. A vacuum pump sucks contaminant-laden air into the module, the air-stream strikes the cone, spins into a cyclone, deposits contaminants on the primary filter below, and goes through the primary filter, eventually through the secondary filter, and finally into the atmosphere. Although this vacuum cleaner minimizes size by artfully combining cyclonic cleaning, contaminant storage, and primary as well as secondary filtration within a single module, its peculiar use of the primary filter surface as contaminant storage site renders it unsuitable for rapid, efficient cleaning of heavily contaminated areas.
(d) U.S. Pat. No. 4,790,865 to DeMarco describes dust collectors employing, among other components, a single cyclone module mounted on a dust collector and another distant but communicating module containing filters; a device accelerating dirty air before it goes through the filters is an optional part of the filter module. Dust-laden air is sucked into the cyclone module, the air spins, deposits dust in the dust collector below, then travels through a hose to the filter module, through the components of the filter module, and finally into the atmosphere. With only one cyclone, this dust collector lacks the power for challenging cleaning operations.
(e) U.S. Pat. No. 4,820,315 to DeMarco describes a complicated vacuum loader of many moving parts, employing, among other things, (1) a prior art cyclone-producing module mounted on a bagger, which collects and packages contaminants in bags, (2) a second prior art cyclone-producing module, communicating with the first, mounted on another contaminant storage module, (3) a complex device, comprising dual valves, tubes and hoses, for transferring contaminants gathered in the contaminant storage module back to the bagger, (4) a third module containing primary filters mounted on the second cyclone module, and (5) a fourth module containing secondary (HEPA) filters, distant from the module containing the primary filters but communicating with it through a pipe or hose. (The patent also describes another similar vacuum loader, which lacks the fourth module housing the secondary filters, and which places either primary or secondary filters in the third module.) In operation contaminant-laden air is sucked into the first cyclone chamber, the air spins, deposits contaminants into the bagger below, enters the second cyclone chamber, spins, deposits additional contaminants into the collection module below, then goes through the primary filters above, through the pipe or hose, through the module containing secondary filters, and eventually into the atmosphere. Contaminants gathered in the collection chamber below the second cyclone are transferred back to the bagger, through operation of the complex device mentioned above, and eventually bagged.
Although this DeMarco loader features two communicating cyclone chambers, it comes with many components and great complexity, which combine to decrease usefulness in several ways.
First, cleaning the secondary (HEPA) filters of the loader, an important maintenance task, can be messy and dangerous, because the secondary filters are separate from the primary filters, in a distant module lacking a contaminant storage chamber. For to clean these secondary filters, the filters must first be taken out of the module housing them. And when they are taken out and cleaned, contaminants adhering on the filters fill the air and proceed to land nearby, which is primarily the face of the person cleaning the filters. Contaminants, especially toxic contaminants, on the face or in the lungs of the operator of the loader, every time the secondary filters need cleaning, is an important limitation of the DeMarco loader.
Second, the loader is less durable and more expensive to maintain than it could have been, because it has many moving parts which do not participate in air cleaning and contaminant storing, such as valves, pistons, a complicated device operating the bagger, etc.
Third, the loader features low design and construction economy with respect to air cleaning and contaminant storing, because most components of the loader neither clean air nor store contaminantsxe2x80x94instead, they perform functions such as transferring contaminants from a storage site to a bagger, operating the bagger, etc. This low design and construction economy brings disadvantages, including relatively (1) low efficiency, (2) low capacity, (3) high structural and operational complexity, (4) high purchase price, and (5) expensive maintenance. Indeed these disadvantages can be seen in action in the requirement for an unusually powerful vacuum-producing motorxe2x80x94a 80 hp motorxe2x80x94for production of a relatively low vacuumxe2x80x94217 inches on the water scalexe2x80x94inside this loader. Design and construction limitations seriously limit the cleaning power of this loader.
Due to limitations relating to cleaning power, maintenance, durability, capacity, efficiency, cost, and operability, the DeMarco loader is no solution to the challenge of large-scale environmental remediation. This challenge requires a vacuum system that is powerful, simple, easy to maintain and operate, durable, of high capacity and efficiency, and of low cost.
Using extensive prototype building and testing, findings made over three decades of work in the fields of industrial infrastructure maintenance and environmental remediation, and certain theoretical principles discussed in Section 6.6, a novel, much-needed vacuum collector for surface decontamination or cleaning was developed. This vacuum collector provides novel, small- and large-diameter cyclone generators, and harnesses the cleaning power of multiple, cooperating cyclones to achieve safe, relatively inexpensive, virtually nonstop decontamination. With these capabilities, the invented multiple-cyclone, i.e., polycyclonic, collector advances the goals of environmental remediation across the globe.
The invented vacuum collector comprises a series of at least two fluidically communicating cyclonic drums, each capable of cleaning contaminant-laden air by both spinning it into a cyclone of unique shape and collecting the contaminants deposited by the cyclone""s centrifugal forces. The first drum in this series has a side wall, a bottom wall, and a moveable cover. To the cover of the first drum is mounted a structure defining a cylindrical chamber which communicates with the drum; this is the cyclone-producing head, or xe2x80x9cthe headxe2x80x9d of the first drum. The head has an inlet port, which is connected to a suction or vacuum hose, and a suitably bent outlet port, which is connected to an inlet port on the next drum of the series of fluidically communicating drums through a segment of vacuum hose. The last drum of the series of fluidically communicating drums is smaller than the first. To this drum is mounted a stack of three communicating cylindrical modules: a covered motor housing containing vacuum-producing motors atop a HEPA filter housing containing a HEPA filter atop a primary filter housing containing primary filters made of singed polyester felt. The last drum employs a novel, large-diameter cyclone generator, which comprises a cylindrical region between the drum side-wall and the primary-filter housing side-wall as cyclonic chamber and an aerodynamically shaped pipe segment feeding contaminant laden air along a tangent to this cyclonic chamber.
In operation the vacuum-producing motors evacuate the interior of the collector, the resulting vacuum sucks air mixed with contaminants off a contaminated surface through the suction hose, and the contaminant-laden air streams into the cyclone-producing head of the first drum of the series wherein a small-diameter cyclone packing huge centrifugal forces forms. This cyclone bursts into the chamber below defined by the first drum and deposits most of the contaminants therein cleaning the air stream. The cleaned air stream exits through the bent outlet port on the head and ultimately reaches the last drum of the series, where, after cleaning by large-diameter cyclonic action, it sequentially passes through the primary and HEPA filters, which are proximately positioned above the mouth of the last drum, and exhausts through the motors, almost contaminant-free.
It is easily seen that the purity of air going through the filters above the last drum increases with the number of cyclonic drums in the collector, especially where the collector employs cyclonic chambers of different cleaning selectivities. Thus, the invented collector enables control of purity of air going through filters, which air purity determines filter lifetime. And since filter clogging is a primary cause for interrupting vacuum cleaning, and costly filter replacement a main contributor to cleaning cost, the invented collector enables environmental remediation that is both virtually nonstop and relatively inexpensive.
Further objects and advantages of the invented vacuum collector include:
1. Multiple, invented cyclone generators, which produce cyclones of variable contaminant-cleaning selectivities working cooperatively to clean the same contaminant-laden air stream.
2. Novel, aerodynamically-optimized, small-diameter cyclonic heads mounted on large drums, producing and propagating extremely compressed, powerful cyclones. Thus, the high contaminant-processing capability of the small-diameter cyclone is uniquely combined with the high contaminant storing capacity of the large drum to produce a cyclonic drum isolating large amounts of densely packed contaminants per unit time.
3. A novel, aerodynamically-optimized, large-diameter cyclone generator, comprising a specially configured inlet port, which tangentially feeds a contaminant-laden air stream into a narrow cylindrical-shell-shaped chamber formed by the side wall of a primary filter housing positioned inside a drum and the side wall of this drum.
4. Primary filter bags made of singed polyester felt capable of filtering off better than 99% of contaminant particles over 1 micron in diameter for extended periods of time; they can be cleaned remotely without exposing the operator to the contaminants they trap.
5. Most proximate disposition of contaminant collection chamber, cyclone chamber, primary filters, and HEPA filters, which disposition maximizes collector efficiency and capacity while minimizing collector size.
6. Virtually nonstop, inexpensive environmental remediation. Increasing the number, and changing the type, of cyclone generators in the polycyclonic collector dramatically increases the purity of the air going through the filters of the collector, stretching their lifetime. Since filter change and maintenance is disruptive and expensive, the invented polycyclonic collector enables virtually nonstop and inexpensive environmental remediation.
7. Safety. The operator of the vacuum collector, and the area around the operator, are not exposed to the harmful contaminants being removed, because the air the collector discharges is essentially contaminant-free, and because collector filters can be cleaned without exposing the operator to the contaminants.
8. Simple, modular design and construction resulting in great operational flexibility as well as mobility enabling the cleaning of hard-to-reach sites (e.g., hilly, rocky, or precipitous sites, etc.).
9. High durability, because the polycyclonic collector has no continuously moving components, other than the parts of the vacuum-producing motors.
10. Maximum Design and Construction Economy with respect to cleaning and storing contaminants, since all collector components clean air and store contaminants, resulting in (1) high efficiency, (2) high capacity, (3) low machine complexity, (4) low purchase price, and (5) low maintenance cost.
11. Widespread applicability. With unprecedented performance and versatility, the invented polycyclonic collector enables remediation in the fields of industry, construction, maintenance, mining, energy, and elsewhere. Materials that the polycyclonic collector can easily remove include dusts, e.g., toxic dusts, sands, asbestos, heavy metals, and toxic chemical compounds, among others.
Thus, a novel polycyclonic collector has been invented, which saves the environment, protects health, and insures enforcement of the federal environmental laws.